[gentoo-dev] [RFC] toolchain-funcs.eclass / toolchain-glibc.eclass - gcc-6 bugfixes and updates

[Matthias Maier]

Hello all,

this is a series of patches against the toolchian-funcs and toolchain-glibc
eclasses, most notably

 - introducing new tc-enables-pie(), tc-enables-ssp(),
   tc-enables-ssp-strong() and tc-enables-ssp-all() functions in
   toolchain-funcs compatible with gcc >=6 and clang as a replacement for
   the old gcc-specs-* functions (patch 1).

   After this patchset is merged, I will follow up with fixes to a (small)
   number of ebuilds and eclasses utilizing the old gcc-specs-* functions
   so that we can deprecate those relatively quickly.

 - updates toolchain-glibc to use said new variants and removing obsolete
   configuration logic for gcc >=6. [1]

 - enables a number of (upstreamed) security features for glibc-2.25 per
   default. [2,3]

Best,
Matthias

[1] https://bugs.gentoo.org/show_bug.cgi?id=618160
[2] https://bugs.gentoo.org/show_bug.cgi?id=621742
[3] https://bugs.gentoo.org/show_bug.cgi?id=609048